Charles hugh dttfey



Dec. s, 1931. 1 `C; H. DQFFY Re. 18,281

" RADIO LoUD'sPEAKER original Filed Jude 5o, 195o J5 nu mi a smllll INVENTOR l CAQ/s M74 DW y Reissued Dec. 8, 1931 UNITED STATES CHARLES HUGH DUFrY, or man, FLORIDA RADIO LOUD SPEAKER OriginalNo. 1,818,987, dated August 18, 1931, Serial 110,464,788, filed June 30, 1930. Application for reissue led October 13, 1931. Serial No. 568,616.

(GRANTED-UNDER THE ACT F MARCH 3, 1883, AS AHENDD APRIL 30, 1928 370 0. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the,

ings or by other known means, becaused to be pitched to a high resonance in order to ac-' 'centuate the reproduction of the high frequenciesand slight the value of the lows, or it vmay be pitched to a low resonance to accentuate the reproduction of the low frequencies and slight the value of the highs. Such a system however does not contemplate an accentuation of both the high and lowA frequencies at the same time, nor does it provide for the variations of simultaneous accentuations of both high and low frequencies.

In the present invention, I prefer to employ a plurality ofadjacent diaphragm driv- 1ng units,'or pulsating currentimpulse responsive devices, referably two, each of which has prefera ly three field windings. One of the windings being of a relatively low impedance or ohmagemesistance in ,order to let through the high frequency pulsations and relatively restrict the lows. rIhe other of the windings being of a relatively medium imv 'pedance or ohmage-resistance so as to let through the high and low frequencies with equal facility and thus pitch the reproduction at medium values. The other of the windings being of a relatively high impedance or ohmage resistance so as lto restrict the highs and letthrough the lows to pitch the lreproduction to a` low resonance.

In the example shown in the accompanying drawings, two such diaphragm driving units are illustrated. f, f c

By such anl arrangement, and by the'construction which will be presently described,

- the reproduced sound may be pitched and composited or blended to produce six different tonal changes, while by reasonof the instrumentality provided for causing the driving units to deliver simultaneous but opposed pulsations to the vibratory diaphragm, or adjacent diaphragm, these six Figure l is a diagrammatic view of one example of the component parts of the system Figure 2 is a front elevation of the selective switch;

ligure 3 is a rear elevation of the same; an

Figure 4 is a cross sectional view through the same.

Like numerals of reference indicate the same `parts throughout the several figures, in which: v

R represents the receiver, and 1 and 2 represent the wires through which the pulsating current is delivered therefrom.

As shown in the example illustrated in Figure 1, the wire 1 passes to the three field windings of the diaphragm drive unit A, and also to one center pole 3 of the reversing switch S. The other wire 2 passes toa bindv ing post 4 ofthe selective switch T, and also to the other of the central poles 5 of the reversing switch S.

Connecting a pole 6 of the reversing switch S with a binding post 7 of the selective switch T, is a wire 8.` Three switch binding posts 9, 10 and 11, Figure 3' are connected by wires 12, 13 and 14 to the three taps 15, 16 and 17 of the three field windings 18, 19 and 20 of the drive unit B, while three switch binding posts 21, 22 and 23 are conl nected by wires 24, 25 and 26 to the three taps 27, 28 'and 29 of the three field windings 30, 31 and 32 of the drive unit A.

Connecting the .pole 33 of the reversing switch S with the three field windings 18,19 and 2O of the drive unit B, is a wire 34. The poles 35 and 436 of the reversing switch S are connected to the poles 6 and 33 thereof by crossed wires as diagrammatically shown, or the reversal of the direction of flow of pulsating current from the receiver R to the drive unit B may be effected by any other known means.

Referring now to the selective switch T, it will be seen from Figures 2, 3 and 4 of the drawings that the same embodies an insulating base 37, and insulating arm 38 carried on ya shaft 39 centrally mounted in the base 37. y

Arcuately arranged on the base 37, are two series of switch contacts A and B', Each of the contacts of these series have preferably semi-spherical heads standing above the plane of the base 37, and each series comprises live and dead contacts alternately arranged, the dead contacts being shown black. In the series A the first and last or end contacts are live, each alternate contact being dead, while in series B', the first and last or end contacts are dead, each alternate contact being live. The result of this arrangement is that a live contact of one series is diametrically opposite to a dead contact of the other series, and a dead contact of one series is diametrically opposite to a liv'e contact of the other series. The four live contacts of series A' are indicated b y the characters a', a2, a3 and a, while the three live contacts of series B' are indicated by the characters b', b2 and b. The dead contacts of both series are indicated by the letter d.

Arranged intermediate the series of contacts A and the central shaft 39 is an arcuate or segmental stationary contact A2, common to the series A', and supported at each end in two posts 4 which form stops for the insulated arm 38,l oneof whichposts forms a binding post for the wire 2 from the rcceiver R.

Intermediate the series of contacts B and central shaft 39 is.an arcuate or segmental stationary contact Bz'common ,to the series B' and supported at each end in two posts 7, one of which forms a binding post for the wire 8 from the reversingl switchV S.

The insulated contact-carrying arm 38 extends over the two arcuate or segmental contacts A2 and B2 and carries at each end there- 'of a spring double contact or brush. One of these A*i is formed, for instance, as shown in Figure 4, the outer end terminating in a V- shaped contact or brush to engage the series of contacts A', while the inner end isl curved as shown and engages the common arcuate or segmental contact A2. The other of these spring double contacts B3 is formed, for 11'1- stance, as shownin Figure 4, the outer end being Hat and bifurcated (Fig. 2) to engage the series of contacts B', -while the inner end is curved as shown and enga es the common arcuate or segmental contact 2.

`Having thus described the construction,

contact A is in electrical contact with the live end contact and the adjacent dead contact of series A', while it will be understood from Figure 4, the inner end of the spring contact A3 is always in electrical contact with the common arcuate or segmental contact A2.

It will be seen from Figure 2 that the flat bifurcated end of the spring contact B3 is wide enough tomake contact with two of the contacts of series B', and when the V-shaped end of contact Aa is in contact with two live and dead contacts of series A', the flat bifurcated end of spring contact Bs is in ycontact with two live and dead contacts of series B', while the inner curved end of spring contact Ba is always in contact vwith the common arcuate or segmental contact B2 (Fig. 4).

The switch being in position shown in Figure 2, the circuit from the receiver R passes to the drive unit A or pulsating current impulse responsive device through the selective switch T. This circuit is through'wire 2 f from receiver R .to binding post 4 of the common arcuate or segmental contact A2 and through the spring double contact A3 to the switch contact a' and through' the wire 24 to the tap 27 of the low impedance field winding 30, which for instance may be of the order of 500 ohms. This winding pitches the drive unit A or impulse responsive device to'a high resonance. K The circuit from the receiver R to'the drive unit B passes through the Wire 2 to the central pole 5 of the reversing switch S andto the binding post 33 of the reversingswitch and through the wire 34 to the low impedance field winding 18 and through thewire 12 to the switch' contact b' of series B; then through the spring double contact Bs to the common arcuate or segmental contact B2 and its binding post 7 through the wire 8 to the pole 6 of the reversing switch S. vFrom the center Vpole 3 .of the reversingswitch S the circuit leads tothe receiver RI It, will thus be seen that when the selective switch T-is in position shown in Fig. 2, the low impedance windings of both drive units A and B are in circuit, which pitches both drive units 6r impulse responsive devices to ay high resonance. It will also be seen .that when thecentral poles 3 and 5 of the reversing switch S are connected to the poles 6 and 33 as in the circuitA linst described,the direc- '-tion of flow ofthe pulsating current from the receiver R to the drive unit B is the reverse of that to the 'drive unit A. This causes positive impulsesv of .drive unit A to be simultaneously accompanied b negative impulses of drive unit 5B.- 4When t e units A and B are `or diaphragms. The acoustical effect of this diaphragm action is that diaphragm and unnatural resonance is eliminated, the audibility of the low frequencies is impaired and the moderate and high frequencies are sharpened. When the action of one of the drive units is thus reversed, the effect is particularly favorable to the reproduction of the speaking voice, where the elimination of fuzzy resonance is desirable and sharpness and definition of the spoken words essential.

lReferring again to Figure 2, it will be seen -that as the arm 38 is moved clockwise, the

- maintained. The movementl is thereforeaclco' companied by no break nor interruption in the reproduction, as the entire output .from the receiver R is passing to thedrive unit B during the brief period. The clockwise movement being continued, the said V-shaped end of the spring contact A3 drops down between the dead contact d, over which it has ridden, and the next adjacent live contact a2 and establishes electrical contact with the live contact a2. At the same time, the bifurcated fiat end of the spring contact B3 passes over the livecontact 'b' and on tothe adjacent dead contact d without breaking contact with said live contact b. The drive unit B is thus maintained in its circuit, but a new circuit has been established for the drive unit A. The switch contact a2 of series A is connected to the highest impedance field winding 32 of the drive unit A, by the wire 26 and this field windin is thus brought into the circuit. This pitc es the drive unit A to its lowest resonance, while the drive unit B is still pitched to its highest resonance. The

acoustical effect of this combination is that the fullest range ofwhich the system is capable is obtained. The high frequenciesare reproduced at their maximum by thev drive unit B, while the low frequencies are reproduced at their fullest values bythe drive unit A. Ari audible click is produced at the,

instant the V-"shaped end of the spring contact A drops down into contact with the live switch contact a2 and the tension of the spring contact A is sucient to maintain both contacts A2 and B2 against casual movement in either direction.

When it is desired to change to any of the other combinations to modify the resonance of the reproduction, as for instance to pitch the same to the lowest resonance of which the system is capable, the arm 38 is again moved clockwise. This causes the V-shaped end of the s ring contact Aa to ride up on the live switc contact a2 and maintain its contact therewith. At the same time the bifurcated flat end'of spring contact B8 breaks contact with the live switch contact b. and passes over the adjacent dead contact d. These movements result in maintaining the drive unit A in circuit and breaking the circuit of the drive unit B, so that during this brief interval, the reproduction is unbroken and uninterrupted. Continued movement of the arm 38.clockwise causes the V-shaped en'd of the spring contact A3 to drop down between the live switch contact a2, with .which it is in contact, and the adjacent dead contact d, thus maintaining contact with said live switch contact a2 and maintaining the highest impedance field winding 32 of the drive unit lA in circuit. At the same time the bifurcated fiat end of spring contact -B3 passes into electrical contact with the adjacent live switch contact b2 and connects the highest impedance field winding 2Q of the drive unit B in the circuit through the wire 13. This changes the pitch of the resonance of the drive unit B from the highest to the lowest and as the corresponding. highest impedance field winding 32v of the drive unit fA 1s maintained in circuit as just described,

both drive units A and B are pitched -to their lowest resonance.

` Further selective movement of the .arm 38, maintains the drive unit B in circuit to continue the reproduction without break or interruption and after momentarily breaking the circuit of drive unit A, establishes another circuit by bringing the intermediate field winding 3l of drlve unit Ainto circuit through the switch contact a3 and the wire 25. This movement maintainsA the pitch of the drive unit B at its lowest resonance and changes the pitch ,of the drive unit A to a medium resonance.

Further movement of the arm 38 maintains the drive unit B in circuit to continue the reproduction without break or interruption, but establishes another circuit for drive unit A in which the low impedance field winding of the drive unit A is brought in circuit. This pitchesthe drive unit A to a high resonance and maintains the drive unit B at a medium resonance. n

It will be seen from Figure 3 illustrating a rear view of the selective switch shown in Figure 2 that the two endmost live contacts of series A', which as will appear from Figure 2 are contacts a and a, are electricallyconnected together; Consequently when the movable contact Ai is in contact with either of these two endmost live contacts a and a4, the same circuit to the drive unit A is closed 5 through the Wires 2 and 24, as will be apparent from Figure 3. For instance from Figure 2, it will be seen that while contacts B2 and b are connected as shown, Contact A2 and a are connected, but as contacts a and a4 are electricallyv connected (Figure 3), the circuit is the same as if the movable contact As were in physical contact with the contact A4.

l It will be noted that in the operation of mtheselective switch T, to change from one point to another the circuits oft' the drive units A and B are alternately broken, and that at no time is there any break in the reproduction., because while the switch is Changing one of the drive units from one pitch resonance to another, the circuit of the other of the drive units is maintained unbroken.

In the example shown in which the drive units are each provided with three field windings of different impedances, six combinations are obtainable to effect six different tonal changes in the reproduction by the selective switch T. As each of these combinations can be again changed by the reversing switch S, a total of twelve different tonal changes is available in the example shown.

As it is necessary that the impulse respona5 sive devices be sufficiently close together so that the sound reproduced at one of them is composited or blended with the sound reproduced "at the other impulse responsive device,

it may be said that the impulse responsive de 40 vices are adjacent when that result is'ac- `complished. l

While I have disclosed one example of the system, the pitch of the resonance of the two drive units or impulse responsive devices 45 may be changed in any known manner other than by different or tapped field windings, as for instance -by fixed or variable conden' sers, and the units or impulse responsive devices selectively brought' into various combinations as bya selective switch such for instance as herein described. i

Having thusdescribed one example of the invention, what I claim as new and desire to secure by Letters Patent of the United States 1. A drive systemk for radiclo11d speaker i diaphragms and the like including two adja cent diaphragm actuating units, each of which includes a lurality of field windings D of different impe ances, a source'y of pulsatv ing electric current, an electrical-circuit, a se' lective switch including two series of switch contacts, one series of 4said contacts for each actuating unit and for electrical connection "5 with the plurality of field windings o f each actuating unit, and a reversing switch in electricalcircuit withl one of the actuating diaphragms and the like, including two ads jacent diaphragm actuating units, each of which includes a plurality of field windings of different impedances, a source of pulsating electric current, an electrical circuit, a selective switch including two series of switch contacts for electrical` connection with the plurality of field windings of the actuating units, whereby any one of the field windings `of one actuating unit may be connected iny circuit with any one of the field windings of the other actuating unit, and a reversing switch in electrical circuit with one of the actuating units, whereby the direction of flow of pulsating current through the field windings of one unit may be reversed with respect to the direction of flow of pulsating current through the field windings of the other of the actuating units. p

3. A drive system for radio loud speaker diaphragme and the like, including two adjacent diaphragm actuatngunits, each of which includes a plurality of field vwindings of different impedances, a source of pulsatingI electric current, an electric circuit, a selective switch including two series of switch contacts for electrical connection with the plurality of field windin s of the actuating units, whereby any one o the field windings of one actuating unit may be connected in circuit vwith any one of the field windings of the other -actuating unit;

4,. A drive system for radio loud speaker diaphragms and the like, including two adjacent diaphragm actuatingunits, each of which includes a plurality of field windings of different impedances, a`n electrical circuit, a selective switch including two seriesi of switch contacts for electrical connection with the plurality of field windings of the actuf' ating units, whereby any one of the field windings of one actuating unit may be connected in circuit with any one of thefield windings of the other actuating unit.

5. A drive system for radio loud speakers` and the like, including' two adjacent dial phragm actuating units, an electrical circuit, means for imparting to each of the two units a plurality yof different pitch resonances, and a selective switch -for selectively connecting the two units in the circuit to impart to each of them the same pitch' resonance, or to img part to oneof them a certain pitch resonance and to the other of them a different pitch resonance.

6. A drive system for radio loud speakers and the like including two adjacent diaphragm actuating units, an electrical circuit, means for imparting to each of the two units a plurality of different pitch resonances, and

means for selectively connecting the two units in the circuit to impart to each of them the same or different pitch resonances.

75 A drive system for radio loud speakers and the like, including two adjacent pulsating current impulse responsive devices,'an electrical circuit, means for imparting to each of the two impulse responsive devices a plurality of different pitch resonances,and means for selectively connecting the two impulse responsive devices to impart to each of them the same or different pitch resonance.

8. A drive qsystem for radio loud speaker diaphragms and the like, including two adjacent diaphragm actuatingmnits, each of which includes a plurality of field windings of different impedances, an electrical circuit, a selective switch including two series of. switch contacts, one series of said contacts for each actuating unit and for electrical connection with the plurality of field windings of each actuating unit, switch contacts movable over both series of switch contacts to selectively engage a contact of each series of switch contacts to bring any one of the field windings of one unit and any one of the field windings of the other unit in the electrical circuit, and a reversing switch in electrical circuit with one of the actuating units', whereby the direction of flow of the current through the selected field winding of one unit may be reversed with respect to the direction of flow of the current through the selected field winding of the other of the ac-I tuating units. l

9. A drive system for radio loud speaker diaphragms and the like, including two adjacent diaphragm actuating units, each -of which includes a plurality of field windings of different impedances, an electrical circult, and a selective switch including two series of switch contacts, one series for each actuating unit and for electrical connection with the lurality of field windings of-each actuating unit, switch contacts movable over both series of switch contacts to selectively engage a contact of each series of switch contacts to bring any one of the field windings of one unit and any one of the field windings of the other unit in the electrical circuit.

10. A drive system `for radio loud speaker diaphragms andthe like, including two adj acent diaphragm actuating units, each of which includes a lurality cf Aeld windings` of different impe ances, an electrical circuit,

and a selective switch including'two'series .cf switch contacts, one series for each actuating-unit, the contacts of each series being/op@ :posite to one another, a switch contact movone of the units to reverse the direction of.

flow of current to one unit with respect tothe other unit.

l11. A drive system for radio loud speaker diaphragms and the like including two adjacent diaphragm actuating units, each of which includes a'r lurality of. field windings of different impe ances, an electrical circuit and a selective switch including two series of switch contacts, one series for each actuating unit, the contacts of each series being opposite to one another, switch contacts movable over both series of switch contacts to selectively engage opposite switch contacts of. each 'series to bring any one of the field windings of both units in the electrical circuit.

12. A drive 'system for radio loud speaker diaphragms and the like, including two adjacent diaphragm actuating units, an electrical circuit, the units including a plurality of yfield windings of different impedances, a selective switch including a series of switch c011- ings, and also including in alternate arrange- .i

ment with the live contacts a plurality .of dead contacts, the live contacts of one serles being diametrically opposite the dead contacts of the other series, an arm vhaving contacts movable over each series of contacts, the movable contacts being of a width to engage a live and a dead contact of eachseries to selectively connect any field winding of one unit and any field winding of the otherunit in the circuit, the herein recited arrangement of switch contacts insuring the holding of a field windin of one unit in the circuit when the connection is broken to a field winding of the other unit as the movable contacts are selectively moved, to the -end vthat the different field windings of the two units may be selectively connected and disconnected 1n the cir- -cuit without interruption or break in the sound reproduction, and means for reversing the direction of flow of the current-to one of the units with respect to the direction of flow of the current tothe other of the units.

, 13. A drive systemfor radio loud speaker diaphragms and the like, including two adj acent diaphragm actuating units, an electrical circuit, the units including a plurality, of field windings of different impedances, a selective switch including a series of switch contacts yfor each unit, each series of contacts includ-.

ing `a live contact for electricall connection with reach of the different field windings and also including in alternate arrangement with the live contacts a plurality ofl dead contacts,

los Y .insuring the holding of a field winding of one unit in the circuit'when connection is broken to a field winding of the other unit, as the vmovable contacts are selectivelyy moved, to

the end that the different field windings of the two units maybe selectively connected and disconnected in the circuit without interruption or break in the soundreproduc-v tion.

f 14. A drive system for radio loud speaker vdiaphragms and the like, including two adj acent diaphragm actuating units, an electrical circuit, each unit including aplurality of field windings of different impedances, a selective switch including a series of switch 'contacts for each unit, each series of contacts including an upstanding live contact for electrical connection with each of the different field windings, and also including in alternate arrangement withy the live contacts, a plurality of upstanding dead contacts, an arm having contacts movable over each series of contacts, the movable Hcontacts being of a width to engage a live and a dead contact of each series to selectively connect any field winding of one unit and any field winding of the other unit in the circuit, one of the movable contacts being V-shaped to drop in between a live and a dead contact of one -series to prevent casual movement of the movable contacts.

15. A drive system for radio loud speaker diaphragms and the like including two adjacent diaphragm actuating units, an electrical circuit, each unit including a plurality of field windings of different impedances, a selective switch in electrical connection with the different field windings of both units, the selective switch including means for selectively connecting any field windingl of one vunit and an field winding of the other unit inthe circuit without simultaneously breaking the circuit through the field windings of both units,'and `means. for reversing the direction of flow of current to one unit with res ect to the direction lof flow of current to t e other unit.

16. A drive sv stem for radio loud speaker diaphragms an the like including two adjacent diaphragm actuating units, an electrical` circuit, each unit including a plurality of` field windings of different impedances, a selective switch in electrical connection with the different field windings of both units, the selective switch including means for selectively connecting any field winding of one unit and any field winding of the other unit in the circuit without simultaneously breaking the circuit through the field windings of both units.

17. A drive system for radio loudspeakers and the like including two adjacent diaphragm actuating units, and including means for imparting to each of the two units' a plurality of different pitch resonances, an electrical circuit and a selective switch including means for electrically connecting in the circuit the means for imparting different pitch resonances to one of the units and for connecting in the circuit the means for imparting different pitch resonances to the other of the two units whereby the sound reproduced by each of the two units may have the same pitch resonance, or the sound reproduced by one unit may have a high pitch resonance andthe sound jointly reproduced by the other unit may have a low pitch resonance.

18. A drive system for railio loud speaker diaphragms and the like including two adj acent diaphragm actuating units and means for imparting to each of the units a plurality of different pitch resonances, an electrical circuit, a selective switch including two series of switch contacts, the contacts of each series being opposite to one another, a switch contact movable over both' series of switch contacts to selectively engage opposite switch contacts of each series to connect in the circuit the meansvfor imparting different pitch resonances to one of the units and to connect in the circuit the means for imparting different pitch resonances toI the other of the units, and means for reversing the direction of flow vof current to one unit with respect to the ldirection of flow vof current to the other unit. y

19. A drive system for radio loud speaker diaphragms and the like, including two adj acent diaphragm actuatingunits and means for imparting to each of the units a plurality of different pitch resonances, an electrical circuit, a selective switch including two series of switch contacts, the contacts of eacli series being opposite tor one another, and Switch contacts movable over both series of contacts to selectively engage opposite switch contacts of each series toconnect in the circuit the means for imparting different pitch resonances to one of the units and to connect in the circuit the means for imparting different pitch resonances to the other of the units.

20. A drive system for radio loud speaker Vdiaphragms and the like, including two adj acent diaphragm actuating units, an electrical v ent pitch resonances, the selective switch including means for selectively conecting'in the circuit the means for imparting diil'erent pitch resonances to one of the units and for connecting in the circuit the means for imparting different pitch resonances to the other of the units without simultaneously breaking the circuit through `the resonance pitching means of both units, and means for reversing the direction of ilow of current through the resonance pitching means of one of the units.

21. A drive system for radio loud speaker diaphragms and the like, including two adjacent diaphragm actuating units, an electrical circuit, the system including means for imparting to each of the units a plurality of different pitch resonances, a selective switch for electrically connecting in the circuit the means for imparting different pitch resonances to one of the units and for electrically connecting in the circuit the means for imparting different pitch resonances to the other of the units without simultaneously breaking the circuit through the resonance pitching means of both units.

22. A drive system for radio loud speaker diaphragms and the like, including two adj acent diaphragm actuating units, an electrical circuit, the system including means for imparting to e-ach of the units avplurality of different pitch resonances, means for electrically connecting in the circuit the means for iinparting a plurality of diferent pitch resonances to each of the units and including means for selectively connecting in thecir'cuit the means for impartingdiiferent p-itch resonances to one of the units and for selectively connecting in the circuit the means for imparting diferent pitch resonances to the other of the units and for maintaining one of the different pitch resonance imparting means for one of the units in the circuit while the circuit is broken through the pitch resonance im.

partin means for the other unit.

23. drive system for radio loud speakers and the like, including a plurality of adjacent pulsating current impulse responsive devices,l

imparting diHerent pitch resonances to another part of the impulse responsive devices and for maintaining in the circuit apart of the impulse responsive'devices whiletlie circuit is broken through a part of the-impulse responsive devices, a'nd means forlfreversing the direction of flow of current to a part of the impulse responsive devices.

24. A drive system for radio loud speakers cuit the pitch resonance imparting means for a part of the impulse responsive devices while the circuit is broken through the pitch resonance imparting means of a part of the impulse responsive devices.

25. A drive system for radio loud speakers and the like, including a plurality of adjacent pulsating current impulse responsive de.-

j vices, an electrical circuit, the system includ- Zing means for imparting to one of the iml pulse responsive devices a plurality of diierent pitch resonances, and means for connecting in the circult the means for lmpartlng different pitch resonances to one of the im-` pulse responsive devices with another of the impulse responsive devices.

26. A drive system for radio loud speakers and the like, including a plurality of adjacent pulsating current impulse responsive devices, an electrical circuit, the system including means for imparting to one of the plurality of responsive devices a plurality of different pitch resonances, means for connecting in the circuit the means for im arting different pitch resonances to one oP the impulse responsive devices with another of the impulse responsive devices, and means in the clrcuit l for reversing the direction of flow of pulsating current to a part of the impulse responsive devices.

27. A drive system for radio loud speakers or the like, includinga pulsating current impulse responsivedevice, and means for selectively imparting thereto a plurality of different pitch-`resonances, an electrical circuit'for the impulse responsive device and another pulsating current impulse responsive device in the electrical circuit and adjacent the irst mentioned impulse responsive device whereby the selected pitch resonance of the first mentionedimpulse responsive device and the pitch resonance of the other re-l sponsive device are composited. Y A

28. A drive system for radio loud speakers or the like, including an electrical circuit,,

a pluralityof pulsating current impulse responsive devices, means for selectively imi parting to the plurality of pulsating current impulse responsive devices, a plurality of different pitch Iresonances to pitch them to whereby their selec-ted pitch resonances' are composlted.

29. A drive system for radio loud speakers or the like, including an electrical circuit, a plurality of adjacent pulsating current impulse responsive devices, means for selectively imparting to a part of the impulse responsive devices :L plurality of different pitch resonances to selectively impart to said lo part pitch resonances different from the pitch resonance of another part of the impulse responsive devices. v l 30. -A drive system for radio loud speakers or the like, including two adjacent pulsating 15 current impulse responsive devices, an electrical circuit, means foriselectively imparting to one of the impulse responsivedevices a plurality of different pitch resonances to impart to it pitch resonances different from 20 the pitch resonance of the other pulsating current impulse responsive device.

CHARLES HUGH DUFFY.' 

